The power button.
it depends on what kind of monitor
computer
OSD Lock Function: To lock the OSD, press and hold the MENU button while the monitor is off and then press power button to turn the monitor on. To un-lock the OSD - press and hold the MENU button while the monitor is off and then press power button to turn the monitor on.
Yes it can. If you have your monitor professionally installed you just have to turn the ignition part of your car on. If your power windows are able to roll down or you are able to turn on your lights etc then the monitor will work.
Check your cord from the computer and monitor. If that is ok check your video card.
If it isn't going into "sleep" mode (in which case just move your mouse), you may have a bad capacitor or diode in the monitor.
To un-lock the OSD - press and hold the Left button while the monitor is off and then press power button to turn the monitor on.
A TV tuner card
notebook
you restart the computer then turn it on again
it would help if you made sense
You can get products that can turn any monitor into a TV with various inputs.